Tuesday, September 28, 1999 Published at 17:09 GMT 18:09 UK
Scientists unveil plastic plants
Conventional plastic is not biodegradable
Biotechnology giant Monsanto says it has created genetically-modified (GM) plants that can grow plastic.
Conventional plastics are made from oil and do not degrade easily.
But the University of Lausanne's Yves Poirer, commenting on the research published in Nature Biotechnology, said: "There is a growing awareness that petroleum is a finite resource and that the indestructibility of plastics can be more of a nuisance than a benefit.
Scientists have long been looking for ways of making plastics that are better for the environment. They have already tried using special strains of bacteria that produce plastic naturally under certain conditions.
But this is a costly process. One kilogram of this plastic would at best cost $3-5, compared with $1 per kilogram for petroleum-derived plastic. Furthermore, the end product is too brittle for most applications.
They have done this by inserting four genes from the plastic-producing bacteria into varieties of oilseed rape and cress. This turns the plants into biological factories making plastic that can then be extracted from the plant.
Also plastic-producing bacteria have to be fed carbon, in the form of glucose, which has been extracted from a crop. In contrast, plants take carbon directly from the air and so the plastic from the GM crops is likely to be relatively cheap.
However, the yield of plastic in the crops is currently only 3%. This is six times lower than has been managed in other experiments.
Monsanto scientists say the next step is to refine the GM process to make it suitable for high-yield production.
This may be possible but cannot be taken for granted. Research programmes by both Monsanto and Zeneca, investigating other approaches to bioplastics, have ended in failure.
Environmental group Friends of the Earth criticised Monsanto's work as little more than a public relations exercise designed to restore the company's image after unfavourable publicity over ita association with GM food crops.
"First Monsanto said it is going to feed the world, now it appears they are going to help solve our waste problems," a spokesman said.
"The long term impact on the environment is unknown and they should not be grown until their absolute saftey is assured."